Tractors, skid steer loaders and other vehicles often carry loaders to which attachments can be connected for various material handling applications. Such loaders, which are usually mounted on the front ends of the vehicles, generally include a pair of laterally spaced side frames, an attachment mounted across the outer ends of the side frames, tilt cylinders coupled between the attachment and the side frames, and lift cylinders coupled between the side frames and fixed uprights by which the loaders are mounted on the vehicles. The lift and tilt cylinders are controlled by the operator of the vehicle to manipulate the attachment as desired.
Since a variety of attachments including scoops, blades, forks, grapples and baskets can be employed with front end loaders, it is desirable to provide a releasable attachment carrier assembly which is both quick and convenient to use. Any such assembly, of course, must be of strong and tight construction since it functions to distribute loads between the attachment and the loader frame; however, other features are also desirable. For example, it is advantageous for the carrier assembly to be configured to facilitate proper alignment and engagement with the attachment as the operator maneuvers the vehicle. Once engaged, it is also desirable to provide some means for quickly and positively locking the attachment to the carrier assembly and then securing the devices in locked relationship for safety purposes to prevent inadvertent disconnection during use.
The devices shown in U.S. Pat. Nos. 4,085,856; 3,964,622; 3,672,521; 3,512,665; 3,034,237 and 2,935,802 are representative of the prior art. U.S. Pat. No. 4,085,856 to Westendorf discloses a quick attach means for end loaders or the like comprising a vertical top pin and a spring loaded lower pin which is responsive to pivotal movement of the boom to automatically lock complementary vertical channel members. U.S. Pat. No. 3,964,622 to Blair, et al. shows a quick change mounting bracket for loader arms comprising a vertical shaft and locking plate which are normally spring biased to a locked position with respect to the lower transverse pin on the attachment. U.S. Pat. No. 3,672,521 to Bauer, et al. shows a quick attachment device, particularly adapted for use with skid steer loaders, which utilizes either pivotal hooks or axially movable wedge members to engage openings in a lower shelf member or lateral flange on the back side of the attachment. U.S. Pat. No. 3,512,665 to Westendorf also shows a quick attach means for end loaders comprising complementary V-shaped portions on the attachment and loader together with vertical top and spring loaded bottom pins for maintaining connection therebetween. Finally, U.S. Pat. Nos. 3,034,237 and 2,935,802 to Wolfe, et al. show multifunction attachment carriers of generally rectangular shape which are adapted to serve as the rear wall of the implement upon engagement therewith by means of pin and slot connections.
Thus, although various attachment carrier assemblies have been available heretofore, the prior devices have not been particularly convenient to use and have not provided adequately for either lateral alignment between the carrier assembly and the implement or positive interlock therebetween after connection. Except for the devices shown in the '521 Bauer and the '856 Westendorf patents, the devices exemplified by the patents discussed in the preceding paragraph require individual manipulation at each lateral side of the attachment. Moreover, the devices of the prior art have tended to be unnecessarily complex and thus expensive and difficult to maintain, and some of the devices incorporating spring secured locking means have tended to become inadvertently disengaged during use.
A need has thus arisen for an improved quick attachment carrier assembly of simplified construction whereby an attachment such as a front end loader can be brought into lateral alignment, connected and positively locked in place more conveniently and in less time than has been possible with the devices of the prior art.